1. Field of the Invention
The present invention relates to power transmission systems and, more particularly, to such systems which are of the all rolling, positive contacting, variable speed type and, still more particularly, wherein extensive load sharing occurs among the load transmitting members.
2. Prior Art
The present invention relates to a transmission system which incorporates oscillator members. It is known in the art to use a wobbling member known as a nutator to effect a fixed gear reduction or speed reduction/increase in a transmission system. Generally representative of the pertinent prior art as it pertains to the present invention are a trio of U.S. Patents, namely, U.S. Pat. No. 4,620,457 to Distin et al., U.S. Pat. No. 3,590,659 to Maroth, and U.S. Pat No. 1,748,907 to Vallance.
U.S. Pat. No. 4,620,457 to Distin et al. discloses a torque transmitting gearing system of the nutating type equipped with a nutating idler member which is in torque transmitting engagement with both a stator and an output gear. Torque transmission between the respective elements is achieved via respective series of rolling, torque transmitting elements in the form of tapered rollers. The rollers are maintained in substantially continuous contact with both their respective driving and driven raceway surfaces, which are formed with trochoidal curvature. Within a given pair of coacting gear surfaces, one surface is shaped with epitrochoidal curvature, and the other with hypotrochoidal curvature.
U.S. Pat. No. 3,590,659 to Maroth discloses a speed changer apparatus with a nutating member having force transfer members in the form of roller elements which nutatively contact inclined surfaces on an action member coupled to an output shaft. The nutating member is prevented from rotation by stationary mounted inclined surfaces which are contacted by force transfer members/The nutating member is peripherally engaged by a rotating driving member coupled to a rotating input shaft. The driving member is provided with a surface shaped to impart nutative motion to the nutating member. Superior axial balance is obtained by operating a pair of nutating sections with opposing axial motions with respect to each other.
U.S. Pat. No. 1,748,907 to Vallance discloses apparatus for transmitting rotary motion from one rotatable element to another rotatable element using a plate, ring, or similar component connected to the rotatable elements using such a construction that rotation of one of the elements causes the plate, ring, or similar component to tilt or oscillate in such a manner that every point in its circumference moves in a lemniscate path and effects rotation of the other one of the elements at an invariable reduced speed or at an invariable increased speed. In greater detail, the Vallance patent discloses a speed reduction mechanism in the form of a nutating gear system, wherein an input shaft initiates wobbling motion of an intermediate member 7, via the engagement of a portion 9b of the intermediate member with an angled or canted portion of the input shaft 2. Radially outwardly on the member 7 are disposed a train of teeth 10 which engage stator teeth 11 formed on a portion of the stationary housing 5. Inside of the cup-member 7 are arranged a number of hemispherical recesses 7b, in which are fixedly seated a like number of balls 8. These balls are in turn in engagement with a continuous curved groove 6b formed in an output member 6. As with other known nutating systems, the engagement between stator teeth 10, 11 prevents the intermediate member 7 from rotating during nutation, so that output rotation is effected solely by means of the engagement between the fixed balls and the groove. As the idler member 7 nutates, the balls 8 successively cam the element 6 rotationally by engaging the walls of the curved groove.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
The present invention discloses, in one embodiment, a continuously variable speed power transmission includes a rotatable input member, a rotatable output member including a plurality of rearwardly directed output face cams thereon. A reaction control rotor mounted for selective rotation about the input axis includes a plurality of forwardly directed reaction face cams thereon in opposition to the output face cams on the output member. A pericyclic motion converter rotatably mounted for nutational motion about the input axis includes a plurality of load transmitting follower members thereon simultaneously engageable with the output face cams and with the reaction face cams. A control mechanism selectively adjusts the rate of rotation of the reaction control rotor relative to the input member such that relative rotation between the reaction control rotor and the input member results in both rotation and nutation of the pericyclic motion converter about the input axis and thereby results in a continuously variable change of ratio of the rotational speed of the output member relative to the input member. In another embodiment, the pericyclic motion converter is rotatably mounted on an encompassing housing. In either event, the load transmitting members of the pericyclic motion converter kinematically under pure rolling contact traverse a mathematically higher order spherical path of action during each revolution of the input member.
The present invention is an all rolling positive contacting mechanical variable speed, power transmission system. It utilizes the fundamental principles of high load capacity and torque transmission efficiency facilitated by high precision rolling element bearings. The concentrated rolling surface contact conditions that prevail in the present invention during torque transmission also facilitates its operation with minimal fluid lubricant. The unique design of conjugate load bearing surfaces in the present invention permits the use of tribologically robust materials and surface film transfer conditions to take place in the concentrated roller contacts. All other known mechanical power transmission systems that employ nutation and various types of gearing arrangements, balls and rollers which engage face cam tooth type surfaces do not possess the unique concentrated rolling conjugate surface contact conditions that are incorporated in the present invention. The present invention is thereby capable of much higher torque density and power transmission efficiency than other known continuously variable mechanical power transmission systems.
The transmission of the invention can be employed in many devices and includes an input member, reaction members driven by the input member, a pericyclic member or oscillator member driven by the input member and a drive output member driven by the pericyclic member, in which the rotation speed of the reaction member and or the pericyclic member can be controlled independent of the input member: thereby, allowing the speed reduction/increase at the output drive member to vary. More specifically, the invention is an all rolling positive contacting mechanical variable speed, power transmission system. It utilizes the fundamental principles of high load capacity and torque transmission efficiency of high precision rolling element bearings. The concentrated rolling surface contact conditions that prevail in the present invention during torque transmission facilitates its operation with minimal fluid lubricant. The unique design of conjugate load bearing surfaces in the present invention permits the use of tribologically robust materials and surface film transfer conditions to take place in the concentrated roller contacts. All other mechanical power transmission systems that employ various types of gearing arrangements, balls or rollers which engage face cam tooth type surfaces do not possess the unique concentrated rolling conjugate surface contact condition that is incorporated in the present invention. The present invention is thereby capable of higher torque density and power transmission efficiency than other mechanical power transmission systems.
A primary feature, then, of the present invention is the provision of a variable speed power transmission which not only produces a certain gear reduction or speed reduction/increase in a transmission using such an oscillator member but which operates to vary the gear reduction or speed reduction/increase in the transmission.
Another feature of the present invention is the provision of such a transmission which results in a continuously variable change of ratio of the rotational speed of the output member relative to the input member.
Yet another feature of the present invention is the provision of such a power transmission which includes an input member rotatable about an input axis, an output member rotatable about an output axis including a plurality of rearwardly directed output face cams thereon, a reaction control rotor mounted for selective rotation about the input axis including a plurality of forwardly directed reaction face cams thereon in opposition to the output face cams on the output member, a pericyclic motion converter rotatably mounted for nutational motion about the input axis including a plurality of load transmitting follower members thereon simultaneously engageable with the output face cams and with the reaction face cams, and an active control device for selectively adjusting the rate of rotation of the reaction control rotor relative to the input member whereby relative rotation between the reaction control rotor and the input member results in both rotation and nutation of the pericyclic motion converter about the input axis and thereby results in a continuously variable change of ratio of the rotational speed of the output member relative to the input member.
Still another feature of the present invention is the provision of such a power transmission in which the output face cams, the reaction face cams, and the follower members of the pericyclic motion converter all employ bevel type gear teeth including internal bevel type gear teeth having a pitch angle greater than 90xc2x0.
Yet a further feature of the present invention is the provision of such a transmission having the construction of the pericyclic motion converter being rotatably mounted on an encompassing housing.
Still another feature of the present invention is the provision of such a transmission in which the load transmitting members of the pericyclic motion converter kinematically under pure rolling contact traverse a mathematically higher order spherical path of action during each revolution of the input member.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings which are incorporated in and constitute a part of this invention, illustrate one of the embodiments of the invention, and together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.